There was controversy recently over how sound data collection procedures in India are, especially when it comes to some of the important national level surveys. An article (by Shamika Ravi, Member of the Economic Advisory Council to the Prime Minister), which was published in a leading national daily on July 7, 2023, cast doubts on the soundness of data collection procedures of some of the surveys such as the National Sample Survey (NSS), National Family Health Survey (NFHS) and Periodic Labour Force Survey (PLFS). The writer proceeded to suggest ‘a major sampling overhaul’ so that the survey estimates reflect the ground reality in the country. In support of her argument, the writer said that from 2011-12 till 2019-21, out of 11 surveys listed in her article, ‘every survey (except NFHS-4 of 2015-16) underestimates the proportion of the urban population or overestimates the rural population significantly’. Consequently, the estimates from these surveys ‘systematically underestimate the improvements across the country’.
The publication of this article led to articles countering her point of view.
It is important to re-emphasise the point that all the surveys listed do adopt scientific sample designs. This is widely acknowledged, even at the international level. However, there can be no denying the fact that there is always a scope for improvement of the sample designs. In fact, the sample designs of the NSS have undergone periodic revisions after due deliberations in the meetings of the NSS round-specific working groups, with final approval by the National Statistical Commission (and by the governing council of the National Sample Survey Office earlier). These committees and bodies have been chaired by or have had as their members some of the most eminent economists, statisticians and demographers that India has ever produced.
